WebRequest.EndGetRequestStream Method (IAsyncResult)

 

When overridden in a descendant class, returns a Stream for writing data to the Internet resource.

Namespace:   System.Net
Assembly:  System (in System.dll)

Public Overridable Function EndGetRequestStream (
	asyncResult As IAsyncResult
) As Stream

Parameters

asyncResult
Type: System.IAsyncResult

An IAsyncResult that references a pending request for a stream.

Return Value

Type: System.IO.Stream

A Stream to write data to.

Exception Condition
NotImplementedException

Any attempt is made to access the method, when the method is not overridden in a descendant class.

The EndGetRequestStream method completes an asynchronous stream request that was started by the BeginGetRequestStream method.

System_CAPS_noteNote

To avoid timing issues with garbage collection, be sure to close the response stream by calling the Close method on the stream returned by GetResponseStream after calling EndGetResponse.

System_CAPS_noteNote

The WebRequest class is an abstract class. The actual behavior of WebRequest instances at run time is determined by the descendant class returned by the WebRequest.Create method. For more information about default values and exceptions, see the documentation for the descendant classes, such as HttpWebRequest and FileWebRequest.

The following example obtains and uses the request stream by calling the EndGetRequestStream. The EndGetRequestStream method completes the asynchronous call to BeginGetRequestStream.

Imports System
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Threading
Imports Microsoft.VisualBasic

Public Class RequestState
    ' This class stores the request state of the request.
    Public request As WebRequest

    Public Sub New()
        request = Nothing
    End Sub ' New
End Class ' RequestState


Class WebRequest_BeginGetRequeststream
    Public Shared allDone As New ManualResetEvent(False)

    Shared Sub Main()
          ' Create a new request.
            Dim myWebRequest As WebRequest = WebRequest.Create("http://www.contoso.com/codesnippets/next.asp")
 ' Create an instance of the RequestState and assign 
            ' myWebRequest' to it's request field.
            Dim myRequestState As New RequestState()
            myRequestState.request = myWebRequest
            myWebRequest.ContentType = "application/x-www-form-urlencoded"

            ' Set the 'Method' property  to 'POST' to post data to a Uri.
            myRequestState.request.Method = "POST"
            ' Start the asynchronous 'BeginGetRequestStream' method call.
            Dim r As IAsyncResult = CType(myWebRequest.BeginGetRequestStream(AddressOf ReadCallback, myRequestState), IAsyncResult)
            ' Pause the current thread until the async operation completes.
            allDone.WaitOne()
            ' Send the Post and get the response.
            Dim myWebResponse As WebResponse = myWebRequest.GetResponse()
            Console.WriteLine(ControlChars.Cr + "The string has been posted.")
            Console.WriteLine("Please wait for the response....")
            Dim streamResponse As Stream = myWebResponse.GetResponseStream()
            Dim streamRead As New StreamReader(streamResponse)
            Dim readBuff(256) As [Char]
            Dim count As Integer = streamRead.Read(readBuff, 0, 256)
            Console.WriteLine(ControlChars.Cr + "The contents of the HTML page are ")
            While count > 0
                Dim outputData As New [String](readBuff, 0, count)
                Console.WriteLine(outputData)
                count = streamRead.Read(readBuff, 0, 256)
            End While

           ' Close the Stream Object.
            streamResponse.Close()
            streamRead.Close()
            ' Release the HttpWebResponse Resource.
             myWebResponse.Close()
    End Sub ' Main

    Private Shared Sub ReadCallback(asynchronousResult As IAsyncResult)
            Dim myRequestState As RequestState = CType(asynchronousResult.AsyncState, RequestState)
            Dim myWebRequest As WebRequest = myRequestState.request
            ' End the request.
            Dim streamResponse As Stream = myWebRequest.EndGetRequestStream(asynchronousResult)
            ' Create a string that is to be posted to the uri.
            Console.WriteLine(ControlChars.Cr + "Please enter a string to be posted:")
            Dim postData As String = Console.ReadLine()
            Dim encoder As New ASCIIEncoding()
            ' Convert  the string into a byte array.
            Dim byteArray As Byte() = Encoding.UTF8.GetBytes(postData)
            ' Write the data to the stream.
            streamResponse.Write(byteArray, 0, postData.Length)
            streamResponse.Close()
            ' Allow the main thread to resume.
            allDone.Set()
    End Sub ' ReadCallback 
End Class ' WebRequest_BeginGetRequeststream 

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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